From: Eric Biggers <ebiggers@kernel.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: syzbot <syzbot+76a43f2b4d34cfc53548@syzkaller.appspotmail.com>,
akpm@osdl.org, deepa.kernel@gmail.com, hch@infradead.org,
jlayton@kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, lkundrak@v3.sk,
syzkaller-bugs@googlegroups.com, tklauser@nuerscht.ch,
trond.myklebust@fys.uio.no
Subject: Re: KASAN: use-after-free Read in mnt_warn_timestamp_expiry
Date: Wed, 16 Oct 2019 19:27:05 -0700 [thread overview]
Message-ID: <20191017022705.GB1552@sol.localdomain> (raw)
In-Reply-To: <20191017015853.GR26530@ZenIV.linux.org.uk>
On Thu, Oct 17, 2019 at 02:58:53AM +0100, Al Viro wrote:
> On Wed, Oct 16, 2019 at 06:47:55PM -0700, Eric Biggers wrote:
> > On Wed, Oct 16, 2019 at 06:42:11PM -0700, syzbot wrote:
> > > ==================================================================
> > > BUG: KASAN: use-after-free in mnt_warn_timestamp_expiry+0x4a/0x250
> > > fs/namespace.c:2471
> > > Read of size 8 at addr ffff888099937328 by task syz-executor.1/18510
> > >
> >
> > Looks like a duplicate of this:
> >
> > #syz dup: KASAN: use-after-free Read in do_mount
> >
> > See the existing thread and proposed fix here:
> > https://lkml.kernel.org/linux-fsdevel/000000000000805e5505945a234b@google.com/T/#u
>
> FWIW, I'd go with your "move mnt_warn_timestamp_expiry() up". However,
> I'd probably turn the message into something like
> foofs filesystem getting mounted at /mnt/barf supports...
> And s/mounted/reconfigured/ if mnt_has_parent(mnt) is already true.
>
> Objections?
>
How about the following?
pr_warn("%s filesystem being %s at %s supports timestamps until %04ld (0x%llx)\n",
sb->s_type->name,
is_mounted(mnt) ? "remounted" : "mounted",
mntpath,
tm.tm_year+1900, (unsigned long long)sb->s_time_max);
I think more people would understand "remounted" than "reconfigured". Also,
is_mounted(mnt) seems like a better choice than mnt_has_parent(real_mount(mnt)).
- Eric
next prev parent reply other threads:[~2019-10-17 2:27 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-17 1:42 syzbot
2019-10-17 1:47 ` Eric Biggers
2019-10-17 1:58 ` Al Viro
2019-10-17 2:27 ` Eric Biggers [this message]
2019-10-17 2:37 ` Al Viro
2019-10-17 2:50 ` Eric Biggers
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